Semicombustible ammunition for open chamber breech mechanism



April 1, 1970 D. DARDI CK 3,507,219

SEMICOMBUSTIBLE AMMUNITION FOR OPEN CHAMBER BREECH MECHANISM Filed Sept. 1. 1967 INVENTOR. DAWD z) .42D/c United States Patent Ofifice 3,507,219 Patented Apr. 21, 1970 3,507,219 SEMICOMBUSTIBLE AMMUNITION FOR OPEN CHAMBER BREECH MECHANISM David Dardick, Palos Verdes Peninsula, Calif., assignor to TRW Inc., Redondo Beach, Calif., a corporation of Ohio Filed Sept. 1, 1967, Ser. No. 665,136 Int. Cl. F21b 43/06; F4211 5/02 U.S. Cl. 102-38 1 Claim ABSTRACT OF THE DISCLOSURE CROSS REFERENCE TO COPENDING APPLICATIONS Reference is made herein to copending application Ser. No. 671,910, filed Sept. 1, 1967, now Patent No. 3,446,113, and entitled Sealed Open Chamber Breech Mechanism and Caseless Ammunition Therefor.

BACKGROUND OF THE INVENTION Field of the invention This invention relates generally to so-called open chamber breech mechanisms and, more particularly, to novel semicombustible ammunition for such breech mechanisms.

As will appear from the ensuing description, the present semicombustible ammunition has both weapon and non-weapon applications. In certain of these applications, the ammunition will contain both a projectile and a propellant charge, while in other applications, the ammunition will contain only a propellant charge. In this regard, attention is directed to the fact that the term ammunition as used in this disclosure is intended to encompass both projectile-type ammunition, i.e. ammunition including both a projectile and a propellant charge, and projectileless ammunition, i.e. ammunition containing only a propellant charge.

Prior art Open chamber breech mechanisms are known in the art. Typical breech mechanisms of this type, for example, are disclosed in Patents Nos. 2,983,223; 3,041,939; 2,831,140; 2,847,784; and 3,046,890.

Generally speaking, an open chamber breech mechanism is characterized by a breech frame containing a rotary carrier or cylinder with one or more firing chambers which open laterally through the circumference of the cylinder. The cylinder is driven in rotation or oscillation to sequentially locate each firing chamber in an ammunition infeed position wherein the chamber is disposed for lateral infeed movement of an ammunition round into the chamber through an ammunition infeed opening in the frame, a firing position wherein the firing chamber is closed by the frame and the breech mechanism is conditioned for firing the round in the chamber, and an ejection position wherein the firing chamber is disposed for lateral ejection of the spent cartridge case from the chamber after firing through an ejection opening in the frame.

One of the major problems encountered in open chamber breech mechanisms involves sealing the breech interfaces against propellant gas leakage during firing. The aforementioned copending application and prior art patents disclose two different techniques for accomplishing this sealing function. The sealing technique disclosed in the application utilizes caseless ammunition including a shaped propellant charge which is totally combustible and separate obturator means on the breech mechanism for sealing the leakage interfaces of the mechanism. The sealing technique disclosed in the prior art patents, on the other hand, employs cased ammunition including a yieldable noncombustible cartridge case, typically constructed of a noncombustible plastic, which contains a propellant charge and is expanded or deformed into sealing contact with the walls of the firing chamber and the breech frames by internal propellant gas pressure to seal the breech interfaces. A particularly unique feature of the breech mechanisms and ammunition disclosed in the patents resides in the complementary, generally triangular shape of the ammunition cartridge case and breech firing chamber which permits the cartridge case to deform, without rupture, into sealing contact With the firing chamber and breech frame walls during firing. This triangular shape of the firing chamber and ammunition has certain other highly important advantages which are fully explained in the patents, and thus need not betreated in detail here. Sufi'ice it to say that among the foremost of these advantages are automatic orientation of each ammunition round in the firing chamber, prevention of jamming of the round between the breech frame and cylinder during rotation of the cylinder to and from firing position, and unrestricted lateral infeed movement of the round into and lateral ejection of its spent cartridge case from the firing chamber.

Each of the two different types of ammunition employed in the prior breech sealing techniques discussed above have certain distinctive advantages and disadvantages which are well known to those skilled in the art. Thus, the prior caseless ammunition eliminates the problem of spent cartridge case disposal, maximizes propellant mass, and minimizes ammunition cost. The prior cased ammunition, on the other hand, accomplishes breech interface sealing with maximum simplicity and minimum cost, is capable of more severe handling during storage, shipment, and firing and is better adapted for use in automatic weapons.

SUMMARY OF THE INVENTION The present invention provides novel semicombustible ammunition for open chamber breech mechanisms of the character described which is superior to both the cased and caseless open chamber ammunition discussed above. Thus, it will become evident as the description proceeds that present ammunition possesses most if not all of the advantages of the prior cased ammunition, particularly simplified breech interface sealing and severe handling capability, and approximates to a high degree the advantages of the prior caseless ammunition, particularly increased propellant mass, simplified spent cartridge case disposal, and reduced ammunition cost. To this end, the invention provides semicombustible ammunition having a yieldable non-combustible cartridge case of the usual generally triangular shape in cross-section containing a propellant charge. The cartridge case is characterized by apex wall sections which extend lengthwise of the case along its longitudinal apex edges and by laterally presented side openings in the regions between the adjacent apex wall sections. This skeletonized cartridge case serves the same functions as the cartridge case of the prior cased open chamber ammunition, to wit, protection of the contained propellant charge during handling and sealing of the breech interfaces during firing. The side openings in the cartridge case serve a two-fold function. First, these openings minimize the total volume of material in the cartridge case and hence the non-combustible mass of the ammunition round. This reduction of the non-combustible mass reduces the ammunition cost and simplifies disposal of the spent cartridge case. Secondly, the openings in the cartridge case provide increased propellant space in the case and thus permit containment of maximum propellant mass.

As noted earlier, the present semicombustible open chamber ammunition has both weapon and non-wea on applications and may contain both a projectile and a propellant charge, or merely a propellant charge, depending upon the particular application of the ammunition. Attention is also directed to the fact that the aforementioned prior art patents disclose two different generally triangular ammunition shapes for open chamber breech mechanisms. It will become evident as the description proceeds that the present semicombustible ammunition may utilize either of these shapes. Accordingly, it will be understood that the expression generally triangular shape employed in the ensuing description is intended to encompass both of the ammunition shapes disclosed in the patents as well as all other similar ammunition shapes. However, the preferred ammunition shape is the generally equilateral triangular round or tround shape disclosed in the majority of the patents. For this reason, the present invention will be disclosed in connection with ammunition of this latter shape.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings:

FIG. 1 is a perspective view of an open chamber gun embodying a typical open chamber breech mechanism and of a present semicombustible ammunition round to be fired in the gun;

FIG. 2 is an enlarged front end view of the ammunition round;

FIG. 3 is an enlarged rear end view of the ammunition round;

FIG. 4 is enlarged side elevation of the open chamber gun in FIG. 1 with parts sectioned for clarity of illustration and showing an ammunition round in firing position in the gun;

FIG. 5 is an enlarged section taken on line 5-5 in FIG. 4;

FIG. 6 is a side elevation of the ammunition round With parts sectioned for clarity of illustration;

FIG. 7 is a section taken on line 7-7 in FIG. 6;

FIG. 8 is a section taken on line 88 in FIG. 6;

FIG. 9 is an elevational view looking in the direction of the arrows on line 9-9 in FIG. 6; and

FIG. 10 is a section through a modified semicombustible ammunition round according to the invention.

4 DESCRIPTION OF THE PREFERRED EMBODIMENTS Turning now to the drawings, there is illustrated a round 10 of semicombustible ammunition according to the invention. Round 10 includes a yieldable non-combustible cartridge case 12 containing a propellant charge 14, and igniter or primer 16, and a projectile 18. The round is intended to be fired in a conventional open chamber gun, such as the gun 19 illustrated in FIGS. 1, 4 and 5. Since the gun 19 is conventional and forms no part of the present invention, a detailed description of the same is unnecessary. Sufiice it to say that the gun has an open chamber breech mechanism 20 including a generally fiat rectangular breech frame 22 having a chamber 24 open ing laterally through opposite sides of the frame. Rotatably mounted in the chamber 24 is a carrier or cylinder 26 containing a firing chamber 28. Firing chamber 28 extends longitudinally of the cylinder and opens laterally through the circumference of the cylinder and longitudinally through the ends of the cylinder. Cylinder 26 is rotatable in the breech frame 22 to locate its firing chamber 28 in an ammunition infeed position (FIG. 1) wherein the firing chamber 28 registers with one open side of the chamber 24 to permit initial lateral infeed movement of a round 10 into the firing chamber, a firing position (FIG. 4) wherein the breech frame firing strap 30 closes the open side of the firing chamber to condition the breech mechanism for firing the round, and a cartridge case ejection position wherein the firing chamber registers with one open side of the chamber 24 to permit lateral ejection of the spent cartridge case after firing. When in firing position, the open front end of the firing chamber 28 registers with a bore 32 extending through a barrel 34 secured to the front end of the breech frame, and the open rear end of the firing chamber registers with a firing mechanism or pin 36 which slides in and is sealed to the rear end of the frame. The breech cylinder 26 is rotated to infeed, firing, and ejection positions by means of a shaft 38 extending rotatably through the rear end of the breech frame.

As noted earlier, a characteristic feature of open chamber breech mechanisms of the kind illustrated resides in the generally triangular shape of the firing chamber 28 in transverse cross-section. In this regard, it will be observed that the inner wall of the breech frame firing strap 30 and the side walls of the firing chamber define included angles of 60 each and are cylindrically curved to the same radius as the circumference of the cylinder 26. Thus, the illustrated firing chamber, when in firing position, has the generally equilateral triangular round shape in transverse cross-section, referred to earlier.

The present invention is concerned primarily with the construction of the ammunition round 10, and particularly of its cartridge case 12. This cartridge case is constructed of a yieldable, noncombustible material and is preferably fabricated from a suitable plastic, such as any one of those disclosed in the aforementioned Patent No. 3,046,890. Cartridge case 12 includes substantially parallel, generally triangular front and rear end walls 40 and 42, respectively, integrally joined by longitudinal apex wall sections 44 which extend between corresponding apices of the end walls, along the three longitudinal apex edges of the case. In the regions between the adjacent apex wall sections 44 are laterally presented openings 46 in the sides of the cartridge case. In this instance, each side of the cartridge case contains a single opening 46 of recetangular shape which extends the full length of the case between its end walls 40, 42. The apex wall sections 44 are essentially relatively slender ribs of generally uniform cross-section from end to end. The two exposed faces of each wall section or rib 44 are flush with the corresponding edge surfaces of the end walls 40, 42. The cartridge case 12 has the same triangular round shape in cross-section as the firing chamber 28 in the breech mechanism 20. In this regard, it will be observed that the edge surfaces of the cartridge case end walls 40, 42 and the corresponding side faces of the apex wall sections or ribs 44 are cylindrically curved to the same radius of curvature as the side walls of the firing chamber and hence to the same radius of curvature as the circumference of the cylinder 26 and the inner wall of the breech frame firing strap 30. Accordingly, when the round is positioned in the firing chamber, the exposed edge surfaces and side faces of the cartridge case end walls and ribs are substantially flush with the circumference of the cylinder.

The projectile 18 of the illustrated ammunition round 10 is positioned on the central axis 48 of the cartridge case 12. Extending through the front end of wall 40 of the case, on the axis 48, is a bore 50 which receives the nose of the projectile. A plastic obturating sleeve 52 surrounds the projectile and has its forward end secured within the bore 50 to provide an effective gas seal between the projectile and the front cartridge case wall 40. The propellant charge 14 of the round comprises a solid propellant which fills the interior space of the cartridge case 12 and encapsulates the propectile 18 and its obturating sleeve 52. According to a preferred feature of the invention, the propellant also fills the side openings 46 in the cartridge case in such a way that the propellant surfaces which are exposed through these openings are flush with the outer surfaces of the case. The primer 16 for igniting the propellant is fixed within an opening in the rear case end wall 42.

It is evident at this point that the cartridge case openings 46 serve the beneficial purposes referred to earlier. Thus, these openings minimize the total volume of material in the cartridge case 12 and, thereby, the mass of non-combustible material of round 10. This reduction in the non-combustible mass, in turn, reduces the weight and cost of the cartridge case and simplifies disposal of the spent case after firing. For example, the spent cartridge case may be conveniently disposed of by grinding the same to a powder. Secondly, the openings 46 maximize the effective propellant space in the cartridge case and thereby permit containment of a greater mass of propellant. The cartridge case itself reinforces and protects the propellant and conditions the round for more severe handling than an uncased open chamber round. In this regard, for example, it is worthy of note that the present ammunition may be fired in an automatic gun.

The present semicombustible round 10 is fired in the usual way in the open chamber breech mechanism 20. Thus, to fire the round, the breech carrier or cylinder 26 is first rotated to infeed position (FIG. 1) and the round is inserted laterally into the firing chamber 28. The cylinder is then rotated to firing position (FIG. 4) and the propellant 14 in the round is ignited by driving the firing pin 36 inwardly against the primer 16. It will be understood, of course, that other firing mechanisms may be employed to fire the round. The high pressure gas generated by the burning propellant drives the projectile 18 forwardly from its obturator sleeve 52 and through the gun bore 32.

As noted earlier, a major problem encountered in open chamber breech mechanisms of this type involves sealing the interfaces of the mechanism against propellant gas leakage during firing. According to the present invention, this sealing function is accomplished by the skeletonized case 12 of the ammunition round 10. Thus, when the round is fired in the firing chamber 28 of the breech mechanism, the resulting propellant gas pressure urges or deforms the front and rear end walls 40, 42 of the case longitudinally of the firing chamber into sealing contact with the confronting front and rear walls 54, 56 of the frame chamber 24 to seal the leakage interfaces between these walls and the adjacent ends of the breech cylinder 26. The propellant gas pressure also urges or deforms the two outer apex wall sections or ribs 44 of the cartridge case laterally against the side walls of the firing chamber and outwardly against the confronting surface of the breech frame firing strap 30 to seal the leakage interfaces between the strap and the circumference of the cylinder. It will now be understood, therefore, that the cartridge case 12 of the present semicombustible round 10 serves the same breech sealing function as does the cartridge case of the conventional cased open chamber ammunition disclosed in the aforementioned patents.

As noted earlier, the propellant charge 14 of the semicombustible round 10 described above is a solid or molded charge. The openings 46 in the cartridge case 12 may thus be uncovered, as shown, since there is no possibility of loss of the propellant through the openings. FIG. 10 illustrates a modified semicombustible round 10a according to the invention which contains a loose grain propellant charge 14a. In this form of the invention, the openings 46a in the cartridge case 12a are sealed by combustible cover means 58a to prevent loss of the loose propellant grains through the openings. The particular cover means illustrated comprises a sleeve which fits snugly within and is adhesively bonded or otherwise secured to the cartridge case. Alternatively, the cover means may com-prise individual sheets which extend across the cartridge case openings and are secured to the case about their respective openings. The combustible cover means may consist of any suitable combustible material of sufficient strength to contain the propellant. Preferably, however, the cover means will comprise a molded or woven propellant material.

At this point, attention is again directed to the fact that while the invention has been disclosed in connection with projectile-type semicombustible ammunition for use in an open chamber weapon or gun, the present ammunition may be used to advantage in open chamber breech mechanisms designed for non-weapon applications. These latter applications will not be explained in detail. Sufiice it to say that exemplary non-weapon applications are stud drivers, nail drivers, stake drivers, slaughter guns, cable splicers, oil well perforators, open chamber solid or liquid propellant pulse engines for space ship attitude control, and in general, a pressurized gas source or generator for any purpose. It will be recognized that .in some of these applications, the present ammunition will contain both a projectile and a propellant charge while in other applications, the ammunition will contain only a propellant charge. Attention is also directed to the fact that while the present ammunition has been disclosed in connection with a simplified open chamber breech mechanism, the amunition may be fired in any of the prior art open chamber breech mechanisms of the class described.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. semicombustible ammunition for an open chamber gun, comprising:

a hollow yieldable non-combustible unitary plastic cartridge case of generally equilateral triangular round shape in transverse cross-section;

said cartridge case having three convex sides, three longitudinal apex edges, and an interior propellant chamber which opens laterally to the exterior of said cartridge case through an opening in each of said convex sides;

said openings being located within the central regions of said convex sides between the ends and said apex edges of said cartridge case to provide a one-piece skeleton cartridge case structure having generally triangular round front and rear plastic end walls and longitudinal plastic sealing ribs integrally joined at their ends to said end Walls and extending between 7 said end walls along the apices of said cartridge case, whereby said ribs form apex edges;

a propellant contained Within said propellant chamber;

said cartridge case having front and rear end wall openings;

a primer fixed within said rear wall openings;

a projectile fixed within the front end of said cartridge case on the axis of said front wall opening with the nose of said projectile positioned within said front wall opening; and

means for blocking propellant gas leakage between said projectile and the wall of said front wall opening.

References Cited UNITED STATES PATENTS Hayner 10238 Howe 102-38 Burney 10238 Young 10238 Kunz 102-38 Quinlan et al. v 102--38 Nadel 10238 SAMUEL FEINBERG, Primary Examiner J. FOX, Assistant Examiner 

